Knitted catheter

ABSTRACT

A medical device, comprising: an elongate tubular knitted catheter comprising at least one biocompatible, electrically non-conductive filament arranged in longitudinally adjacent substantially parallel rows each stitched to an adjacent row.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Australian Provisional Patent Application No. 2008904838, filed Sep. 17, 2008, Australian Provisional Patent Application No. 2009901534, filed Apr. 8, 2009, and Australian Provisional Patent Application No. 2009901531, filed Apr. 8, 2009, which are hereby incorporated by reference herein.

The present application is related to commonly owned and co-pending U.S. Utility Patent Applications entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, “Knitted Electrode Assembly And Integrated Connector For An Active Implantable Medical Device,” filed Aug. 28, 2009, “Bonded Hermetic Feed Through For An Active Implantable Medical Device,” filed Aug. 28, 2009, “Stitched Components of An Active Implantable Medical Device,” filed Aug. 28, 2009, and “Electronics Package For An Active Implantable Medical Device,” filed Aug. 28, 2009, which are hereby incorporated by reference herein.

BACKGROUND

1. Field of the Invention

The present invention relates generally to catheters, and more particularly, to a knitted catheter.

2. Related Art

Medical devices having one or more implantable components, generally referred to as implantable medical devices, have provided a wide range of therapeutic benefits to patients over recent decades. One type of implantable medical device includes an implantable, hermetically sealed electronics module, and a device that interfaces with a patient's tissue, sometimes referred to as a tissue interface. The tissue interface may include, for example, one or more instruments, apparatus, sensors or other functional components that are permanently or temporarily implanted in a patient. The tissue interface is used to, for example, diagnose, monitor, and/or treat a disease or injury, or to modify a patient's anatomy or physiological process. Such devices are referred to herein as active implantable medical devices (AIMDs).

Other types of implantable medical devices include an implantable tubular member, referred to herein as a catheter, having a lumen extending there through. Medical catheters are used by physicians to diagnose and treat a range conditions in a patient's body. Specifically, catheters are used to introduce or withdraw fluids, introduce an instrument, apparatus, or other functional component, delivering electrical stimulation signals to a patient's tissue, etc.

SUMMARY

In accordance with one aspect of the present invention, a medical device is provided. The medical device comprises: an elongate tubular knitted catheter comprising at least one biocompatible, electrically non-conductive filament arranged in longitudinally adjacent substantially parallel rows each stitched to an adjacent row, wherein the tubular catheter has an inner diameter that is sufficient to receive at least one instrument.

In accordance with one aspect of the present invention, a method for manufacturing a knitted tubular catheter is provided. The method comprises: providing at least one biocompatible, electrically non-conductive filament; and knitting the at least one non-conductive filament into an elongate tube of longitudinally adjacent substantially parallel rows, each row stitched to an adjacent row, wherein the tube has an inner diameter that is sufficient to receive at least one instrument.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and embodiments of the present invention are described herein with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary implantable medical device comprising a knitted catheter in accordance with embodiments of the present invention;

FIG. 2 is a perspective view of a section of a knitted member;

FIG. 3 is a side view of a section of a knitted catheter in accordance with embodiments of the present invention;

FIG. 4 is a side view of a section of a knitted catheter in accordance with embodiments of the present invention;

FIG. 5A is a perspective view of a composite conductive filament in accordance with embodiments of the present invention;

FIG. 5B is a side view of a section of a knitted catheter comprising a composite conductive filament of FIG. 5A, in accordance with embodiments of the present invention;

FIG. 6A is a partial cross-sectional side view of a section of a knitted catheter having an active component positioned therein, in accordance with embodiments of the present invention;

FIG. 6B is a side view of a section of a knitted catheter having an active component positioned thereon, in accordance with embodiments of the present invention;

FIG. 7 is a partial cross-sectional side view of a section of a knitted catheter having a steering element positioned therein, in accordance with embodiments of the present invention;

FIG. 8A is a side view of a steering element in accordance with embodiments of the present invention;

FIG. 8B is a side view of a steering element in accordance with embodiments of the present invention;

FIG. 8C is a partial cross-sectional side view of a section of a knitted catheter having steering elements in accordance with embodiments of FIG. 8B positioned therein;

FIG. 9A is a side view of a section of a knitted catheter having a support structure positioned therein, in accordance with embodiments of the present invention;

FIG. 9B is a side view of a section of a knitted catheter having a stylet at least partially positioned therein, in accordance with embodiments of the present invention;

FIG. 9C is a side view of a section of a knitted catheter having an agent delivery mechanism therein, in accordance with embodiments of the present invention;

FIG. 10 is a side view of a section of a knitted catheter having a knitted tubular member positioned therein, in accordance with embodiments of the present invention;

FIG. 11 is a side view of a section of a knitted catheter having a gel therein, in accordance with embodiments of the present invention;

FIG. 12A is a side view of a section of a knitted catheter having an anchoring element therein, in accordance with embodiments of the present invention;

FIG. 12B is a side view of a section of a knitted catheter having an anchoring element therein, in accordance with embodiments of the present invention;

FIG. 13 is a side view of a section of a conductive cuff positioned on a non-conductive support member, in accordance with embodiments of the present invention;

FIG. 14A is a high level flowchart illustrating a method for manufacturing a knitted catheter in accordance with embodiments of the present invention; and

FIG. 14B is a high level flowchart illustrating a method for manufacturing a knitted catheter in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

Aspects of the present invention are generally directed to an implantable medical device comprising an implantable elongate tubular catheter formed using textile or fabric manufacturing methods. Exemplary textile manufacturing methods include, but are not limited to, weaving, knitting, braiding, crocheting, etc. For ease of illustration, embodiments of the present invention will be primarily described herein with reference to forming a knitted catheter. It would be appreciated that other textile manufacturing methods are also within the scope of the present invention.

A knitted catheter in accordance with embodiments of the present invention comprises at least one biocompatible, electrically non-conductive filament arranged in longitudinally adjacent substantially parallel rows each stitched to an adjacent row. In certain embodiments, the knitted catheter has an inner diameter that is sufficient to receive at least one instrument.

Embodiments of the present invention are described herein primarily in connection with one type of implantable medical device, namely a steerable catheter system. It should be appreciated that embodiments of the present invention may be implemented in any implantable medical device comprising an elongate tubular member. For instance, embodiments of the present invention may be implemented in medical devices that are implanted for a relatively short period of time to address acute conditions, as well in devices that are implanted for a relatively long period of time to address chronic conditions.

FIG. 1 is a perspective view of an implantable medical device, namely a steerable catheter system 100, in accordance with embodiments of the present invention. Steerable catheter system 100 comprises an implantable knitted catheter 104, and a handle 130 coupled to the knitted catheter by support member 108. As described in greater detail below, knitted catheter 104 comprises a biocompatible, electrically non-conductive filament arranged in substantially parallel rows each stitched to an adjacent row.

Knitted catheter 104 is configured to be implanted in a patient using, for example, a sleeve or guide tube, while handle 130 is positionable external to the patient. Handle 130 provides a physician, surgeon, or other medical practitioner, (generally and collectively referred to as “surgeons” herein), with the ability to control the operation of knitted catheter 104. More specifically, handle 130 includes user controls 116 which permit a surgeon to control the orientation of distal region 126 of knitted catheter 104.

In the embodiments of FIG. 1, user controls 116 comprise three control knobs 124. As described below, control knobs 124 are mechanically or electrically connected to distal region 126, or one or more components positioned therein, to steer knitted catheter 104. Control knobs 124 may also control the operation of one or more components positioned in or on knitted catheter 104.

Handle 130 further comprises a lumen 122 extending through the center thereof. The proximal end of lumen 122 comprises an opening, referred to as access port 118, for introduction of one or more instruments or other devices into lumen 122.

In the embodiments of FIG. 1, handle 130 is mechanically coupled to knitted catheter 104 by support member 108. Support member 108 comprises a bio-compatible tube extending from handle 130. Support member 108 also has a lumen (not shown) extending through the center thereof. The proximal end (not shown) of knitted catheter 104 is configured to be mechanically connected to support member 108 such that a continuous pathway is created from access port 118 through distal region 126 of knitted catheter 104. As such, the distal end of an elongate instrument introduced through access port 118 may emerge from distal region 126.

It should be appreciated that catheters of various lengths may be formed in accordance with embodiments of the present invention. For ease of illustration, only a section of knitted catheter 104 is shown.

As noted above, a knitted catheter in accordance with embodiments of the present invention comprises at least one biocompatible, electrically non-conductive filament arranged in substantially parallel rows each stitched to an adjacent row. Knitting is a technique for producing a two or three-dimensional structure from a linear or one-dimensional yarn, thread or other filament (collectively and generally referred to as “filaments” herein). There are two primary varieties of knitting, known as weft knitting and warp knitting. FIG. 2 is a perspective view of a section of a knitted structure 220 formed by weft knitting a single filament 218.

As shown in FIG. 2, the generally meandering path of the filament, referred to as the filament course 242, is substantially perpendicular to the sequences of interlocking stitches 246. A sequence of stitches 246 is referred to as a wale 244. In weft knitting, the entire knitted structure may be manufactured from a single filament by adding stitches 246 to each wale 244 in turn. In contrast to the embodiments illustrated in FIG. 2, in warp knitting, the wales run roughly parallel to the filament course 242.

It should be appreciated that embodiments of the present invention may be implemented using weft or warp knitting. Furthermore, embodiments of the present invention may use circular knitting or flat knitting. Circular knitting creates a seamless tube, while flat knitting creates a substantially planar sheet. In certain embodiments in which flat knitting is used, the knitted structure would be disposed around a cylindrical support member as described with reference to FIG. 9A below to provide the desired tubular shape.

Catheters in accordance with embodiments of the present invention may be knitted using automated knitting methods known in the art, or alternatively using a hand knitting process. It should be appreciated that the knitting method, filament diameter, number of needles and/or the knitting needle size may all affect the size of the stitches and the size of the resulting catheter. As such, the size and shape of the catheter is highly customizable.

As noted above, medical catheters are used by surgeons to perform various functions, including the diagnosis and/or treatment of a range of conditions in a patient. In certain embodiments of the present invention, a knitted catheter comprises one or more electrodes positioned on the surface of the distal region of the catheter. In such embodiments, the electrodes are used to deliver electrical stimulation signals to a patient, or record/monitor the physiological response of a patient's tissue to, for example, a therapy. Electrical stimulations signals may be delivered to stimulate tissue, or, in alternative embodiments, for tissue ablation.

FIG. 3 illustrates a catheter 304 having electrodes 306 thereon. In the embodiments of FIG. 3, a non-conductive filament 318 is knitted into longitudinally adjacent, substantially parallel rows 332 each stitched to an adjacent row. As shown, two conductive filaments 312 are concurrently knitted with sections of non-conductive filament 318 such that the conductive filament and the non-conductive filament 318 follow the same course. The concurrently knit sections of conductive filaments 312 are referred to as being intertwined with non-conductive filament 318. The intertwined portions of conductive filaments 312A, 312B each form an electrode 306A, 306B, respectively, that may be used to deliver electrical stimulation signals to, and/or receive signals from, a patient's tissue. Further details of concurrently knitting a conductive filament with a non-conductive filament are provided in commonly owned and co-pending U.S. Utility Patent Application entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, the content of which is hereby incorporated by reference herein.

In the embodiments of FIG. 3, conductive filaments 312A, 312B are configured to be electrically connected to a stimulator unit (not shown) or electronics module (also not shown) positioned external to the patient. As such, a section of the each filament 312 extends proximally from the intertwined portions of the filament through the interior of catheter 304 for connection to the stimulator unit or electronics module.

As noted, the term filament is used to refer to both the conductive and non-conductive threads, fibers or wires that are used to form knitted catheter 304. It should be appreciated that, as shown in FIG. 3, filaments of varying diameters and properties may be used to form catheter 304. As such, the use of filament to refer to both conductive and non-conductive elements should not be construed to imply that the conductive and non-conductive elements have the same diameter or properties.

A variety of different types and shapes of conductive filaments may be used to knit a catheter in accordance with embodiments of the present invention. In one embodiment, the conductive filament is a fiber manufactured from carbon nanotubes. Alternatively, the conductive filament is a platinum or other biocompatible conductive wire. Such wires may be given suitable surface treatments to increase their surface area (e.g. forming a layer of iridium oxide on the surface of platinum, utilizing platinum “blacking,” or coating the wire with carbon nanotubes). In other embodiments, the conductive filament comprises several grouped strands of a conductive material. In other embodiments, the filament may be a composite filament formed from two or more materials to provide a desired structure. In certain such embodiments, the properties of the composite filament may change along the length thereof. For example, certain portions of the composite filament may be conductive, while portions are non-conductive. It would also be appreciated that other types of conductive filaments may also be used. Furthermore, although embodiments of the present invention are described using tubular or round fibers, it would be appreciated that other shapes are within the scope of the present invention.

As noted above, conductive filaments in accordance embodiments of the present invention are intertwined with a non-conductive filament to form the catheter. While a majority of the intertwined portion is an exposed conductive element, the remainder of the conductive filament may be insulated. In one such embodiment, a length of suitably insulated conductive filament (e.g. parylene coated platinum wire) is provided and the insulation is removed from the section that is to be intertwined, leaving the remainder of the filament with the insulated coating.

A variety of non-conductive filaments may be used to knit a catheter in accordance with embodiments of the present invention. In one embodiment, the non-conductive filament is a biocompatible non-elastomeric polymer material. In another embodiment, the non-conductive filament is a biocompatible elastomeric material. For example, the elastomeric material may comprise, for example, silicone, silicone/polyurethane, silicone polymers, or other suitable materials including AORTech® and PBAX. Other elastomeric polymers that provide for material elongation while providing structural strength and abrasion resistance so as to facilitate knitting may also be used. It should be appreciated that other types of non-conductive filaments may also be used.

In embodiments in which an elastomeric non-conductive filament is used, the filament may be knitted under tension to reduce the final size of the catheter, or portions thereof. The knitting of filaments under tension to form a catheter is described in commonly owned and co-pending U.S. Utility Patent Application entitled Knitted Catheter and Integrated Connector for an Active Implantable Medical Device,” filed Aug. 28, 2009, the content of which is hereby incorporated by reference herein.

In a further embodiment, a non-conductive filament comprises a drug-eluting polymer. In such embodiments, drugs appropriate to the application may be incorporated into the structure so as to be automatically dispensed once the catheter is implanted. In alterative embodiments, fibers may be coated with any of a number of materials that provide a therapeutic benefit. For example, in one embodiment the fibers may receive an anti-fibrogenic coating that prevents attachment to tissue. In other embodiments the fibers may be coated with a therapeutic material which promotes healing. In still further embodiments, the non-conductive filament comprises a thermo-softening plastic material, such as polypropylene. As described below, the thermo-softening plastic material allows the knitted structure to be formed into a variety of shapes using, for example, molding, sintering, etc.

FIG. 4 illustrates embodiments of the present invention in which a distal region 426 of a catheter 404 is formed by alternately knitting with conductive and non-conductive filaments. In the embodiments of FIG. 4, a plurality of rows 432A are knitted from a first non-conductive filament 418A and form a first section of catheter 404. A first conductive filament 412A forms a row 432B that is knitted to rows 432A of non-conductive filament 418A. Row 432B of first conductive filament 412A forms an electrode 406A that may be used to deliver electrical stimulation signals to, and/or receive signals from, a patient's tissue.

In the embodiments of FIG. 4B, a second non-conductive filament 418B is knitted to row 432B of conductive filament 412A to form an additional non-conductive section of catheter 404. A second conductive filament 412B forms a row 432D that is knitted to rows 432C of non-conductive filament 418B. Similar to row 432B of conductive filament 412B, row 432D of second conductive filament 412B forms an electrode 406B that may be used to deliver electrical stimulation signals to, and/or receive signals from, a patient's tissue. As used herein, conductive filaments 412A and 412B are referred to as being intertwined with non-conductive filament 418B. Further details of knitting an elongate member using alternating conductive and non-conductive filaments are provided in commonly owned and co-pending U.S. Utility Patent Application entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, the content of which is hereby incorporated by reference herein.

Conductive filaments 412A, 412B are configured to be electrically connected to a stimulator unit (not shown) or an electronics module (also not shown) positioned external to the patient. As such, a section of the each filament 412 extends proximally from the intertwined portions of the filament through the interior of catheter 404 for connection to the stimulator unit or electronics module.

FIGS. 5A and 5B illustrate embodiments of the present invention in which a composite conductive filament is used to form a distal region of a catheter. As shown in FIG. 5A, a composite conductive filament 516 is formed by winding a section of a conductive filament 512 around a section of a non-conductive filament 518. Conductive filament 512 may be loosely or tightly wound onto non-conductive filament 518, and is referred to herein as being intertwined with non-conductive filament 518.

In certain embodiments of FIG. 5A, non-conductive filament 518 comprises a thermo-softening plastic material. The use of a thermo-softening filament allows conductive filament 512 to be wound around non-conductive filament 518 while the non-conductive filament is in a softened state. This ensures that conductive filament 512 is well integrated into non-conductive filament 518 so as to reduce any difference in the size of the stitches in the electrode area when compare to those in the non-conductive areas of a formed catheter. As noted, conductive filament 512 may be loosely or tightly wound onto non-conductive filament 518. A loose winding provides integration of the two filaments and provides a compliant structure to manage fatigue. A tight winding provides substantially the same benefits, but also increases the amount of conductive filament in a single stitch. An alternative composite conductive filament is formed using a cording method as described in commonly owned and co-pending U.S. Utility Application entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, the content of which are hereby incorporated by reference herein.

FIG. 5B is a side view of a distal region 526 of a knitted catheter 504 formed from composite conductive filament 516. In these embodiments, composite conductive filament 516 is knitted into longitudinally adjacent and substantially parallel rows 532. When catheter 504 is formed, the conductive portions of composite conductive filament 516 (i.e. the portions of conductive filament 512 wound around non-conductive filament 518) form electrode 506 that may be used to deliver electrical stimulation signals to, and/or receive signals from, a patient's tissue. Further details of forming an elongate member from a composite conductive filament are provided in commonly owned and co-pending U.S. Utility Patent Application entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, the content of which is hereby incorporated by reference herein.

As noted above, a catheter in accordance with certain embodiments of the present invention comprises one or more electrodes to deliver electrical stimulation signals to, and/or receive signals from, a patient's tissue. In other embodiments of the present invention, a catheter may also, or alternatively, include one or more passive or active components configured to perform a variety of functions. As used herein, an active component refers to any component that utilizes, or operates with, electrical signals. A passive components refers to a functional component that does not utilize, or operate with, electrical signals. Passive components include, but are not limited to, forceps, mechanical biopsy devices, etc. For ease of illustration, embodiments of the present invention will be primarily discussed with reference to active components positioned in or on a knitted catheter. It should be appreciated that the incorporation of passive components into a knitted are within the scope of the present invention.

FIG. 6A illustrates a knitted catheter 604 in accordance with such embodiments of the present invention knitted from a non-conductive filament 618. In FIG. 6A, a section of the exterior surface of knitted catheter 604 is cut away to expose an exemplary location for an active component 644 within distal region 626. For ease of illustration, active component 644 is schematically illustrated by a box. In accordance with embodiments of the present invention, active component 644 may comprise one or more instruments, apparatus, sensors, processors, controllers or other functional components that are used to, for example, diagnosis, monitor, and/or treat a disease or injury, or to modify the patient's anatomy or physiological process. FIG. 6B illustrates an alternative embodiment of catheter 604 in which an active component 644 is mounted on the surface of distal region 626.

In certain specific embodiments of the present invention, active component 644 comprises an agent delivery system for administering drugs, active substances or therapeutic agents (collectively and generally referred to as “therapeutic agents” herein) to a patient. In certain such embodiments, active component 644 may comprise a pump, reservoir and an agent delivery mechanism. In alternative embodiments, active component 644 comprises an agent delivery mechanism that is fluidically coupled to a pump and/or reservoir positioned outside catheter 604. In one such embodiment, a fluid is passed down the length of the catheter for delivery to tissue. In another specific example, active component 644 includes one or more sensors for monitoring, for example, pressure, temperature, etc., within the patient.

In a still further embodiment of the present invention, the catheter is knitted using a non-conductive filament that is an insulated conducting element which is suitable for strain gauge applications. In such embodiments, the catheter may be constructed in one or more sections, each section being able to measure the strain experienced across that section. Other sensing devices may be incorporated into the structure using a similar method.

In another embodiment, active component 644 comprises one or more actuators incorporated into the knitted structure. Suitable actuators may include a low power linear motor. Such an actuator is anchored at a suitable location in catheter 604 and may allow the catheter to, for example, provide a method of applying pressure to an organ or body tissue for therapeutic benefit.

In a further embodiment, active component 644 comprises an enclosed electronics package. In this embodiment one of more electronics packages may be encapsulated in the knitted tube either during its manufacture or afterwards providing a compact and robust final assembly for the whole implantable device.

As noted above, embodiments of the present invention are directed to steerable catheters. FIG. 7 is a side view of one such steerable catheter. Knitted catheter 704 of FIG. 7 comprises a non-conductive filament 718 formed into longitudinally adjacent rows each stitched to an adjacent row. Disposed in distal region 726 of catheter 704 is a steering element 752. As shown, steering element 752 comprises a spring 754 wound between plates 756. Guide wires (not shown) extend froms plate 756 to control knobs 124 (FIG. 1) positioned external to the patient. A surgeon may manipulate control knobs 124 to bend spring 754 in different directions, thereby altering the orientation of distal region 726. In this manner, catheter 704 may steered within the patient's body.

FIGS. 8A-8C illustrates alternative embodiments of catheter 704 in which spring 754 has been omitted. In the embodiments of FIG. 8C, catheter 704 is formed from an elastomeric non-conductive filament 718, and two plates 854 are mounted in distal region 726. FIG. 8B illustrates a side view of a plate 854. As shown, plate 854 has points 860 with mate with stitches of non-conductive filament 718. Connected to plates 854 are guide wires 855 which extend to control knobs 124 positioned external to the patient. By manipulating control knobs 124, a surgeon exerts forces on plates 854 which, due to the use of elastomeric filament 718, causes distal region to 726 to bend.

In the embodiments of FIG. 8C, plates 854 having an aperture 858 in the center thereof that permit one or more instruments to extend there though. FIG. 8A illustrates an alternative plate 852 that does not include an aperture.

It should be appreciated that numerous variations to the arrangements shown in FIGS. 7-8C are within the scope of the present invention. For example, in certain embodiments, guide wires may be replaced with hydraulic mechanisms for manipulating distal region 726.

According to another aspect of the present invention illustrated in FIG. 9A, a knitted catheter 904 may be formed around a hollow biocompatible support structure 952. In the embodiments of FIG. 9A, catheter 904A is knitted from a composite conductive filament 916 that is substantially similar to composite conductive filament 516 described above with reference to FIGS. 5A-5C. The conductive portion of composite conductive filament 916 forms electrode 906.

As shown, support structure 952 comprises a cylindrical member formed from a biocompatible, electrically non-conductive material that is sized to substantially fill the inner diameter of catheter 904A. Because support structure 952 substantially fills the inner diameter of catheter 904, the knitted structure is disposed on the surface of the support structure, and support structure 952 provides additional mechanical strength to catheter 904A. Support structure 952 has a lumen 956 extending through the center thereof to permit the introduction of one or more instruments into catheter 904A.

The inherent ability of the knitted catheter to change diameter as it is compressed or expanded allows support structures 952 of various shapes and diameters to be easily introduced. This process may be further facilitated if composite conductive filament 916 has elastomeric properties.

It would be appreciated that variations of the embodiments of FIG. 9A are within the scope of the present invention. For instance, in one such variation, support structure 952 comprises a shape memory element. In such embodiment, heating elements are integrated into catheter 904A adjacent shape memory element 952 to alter the shape thereof. The change in the shape of memory element 952 alters the orientation of distal region 926.

In still other embodiments, a series of temperature activated shape memory alloy components are mounted within catheter 904A. In such embodiments, the alloy components are electrically connected to a controller in handle 130 (FIG. 1) that selectively delivers electrical current to the alloy components to cause distal region 926 to bend in different directions as the shape-memory alloy components change shape.

FIG. 9B illustrates a catheter 904B in accordance with still other embodiments of the present invention. In these embodiments, distal region 926 of catheter 904B is pre-formed to a first curved configuration. Catheter 904B further comprises a central tube 954 that is configured to receive a stylet 962. While stylet 962 is positioned in central tube 954, stylet 962 retains catheter 904B in a straight configuration. When stylet 962 is withdrawn, distal region 926 returns to the first curved configuration. Stylet 962 may be withdrawn during or following implantation of catheter 904B into the patient.

As noted above, a catheter in accordance with embodiments of the present invention has an inner diameter that is sufficient to receive one or more instruments. It would be appreciated that a variety of instruments may be introduced through a catheter of the present invention. For instance, an endoscopic camera or cameras, lighting instruments, tissue ablation instruments, drug delivery devices, scissors, forceps, biopsy devices, clamps, etc. may all be used in accordance with embodiments of the present invention. It should also be appreciated that any of these devices may integrated in, or disposed on, a knitted catheter as described above with reference to FIGS. 6A and 6B.

FIG. 9C illustrates specific embodiments of the present invention in which an irrigation device 978 is inserted into a knitted catheter 904C. In these embodiments, irrigation device 978 comprises an elongate tube that is fluidically coupled to a pump and/or reservoir positioned outside catheter 904C. A cooling fluid is passed down the length of device 978 for delivery to a patient's tissue via delivery ports 964. In certain embodiments, the fluid is delivered to cool tissue adjacent electrode 906.

FIG. 10 illustrates further embodiments of the present invention in which a knitted catheter 1004 comprises a first tube 1038 knitted from a non-conductive filament 1018. Disposed in the center of first knitted tube 1038 is a second knitted tube 1048 knitted from a non-conductive filament 1028. In the embodiments of FIG. 10, the different tubes 1038, 1048, may be made of different materials to achieve different performance characteristics. For example, softer materials may be used in inner tubes while the outer tube may be constructed from a harder material (i.e. a material having a higher durometer level) for abrasion resistance or strength. In certain embodiments, silicone filaments having different durometer levels may be used.

As noted, a knitted catheter in accordance with embodiments of the present may be used in devices implanted for a short period of time to address acute conditions, as well in devices that are implanted for a relatively long period of time to address chronic conditions. Over a period of time, fibrous tissue may begin to integrate with the stitches of a knitted catheter. Although such integration may be beneficial, integration is not desirable in all circumstances. FIG. 11 illustrates embodiments of the present invention designed to limit tissue integration.

In the embodiments of FIG. 11, catheter 1104 is knitted from non-conductive filament 1118. A biocompatible gel 1170 is disposed at least inside a number of stitches 1172. By filling stitches 1172, gel 1170 provides a barrier to tissue ingrowth. In certain embodiments, gel 1170 may substantially fill the interior of catheter 1104. It should be appreciated that a variety of suitable gels, such as silicone, may be used in embodiments of the present invention.

In certain embodiments of the present invention, it is desirable to secure or anchor a knitted catheter to a patient. As noted above, in certain embodiments, a catheter may be anchored through the growth of fibrous tissue into the catheter stitches. FIGS. 12A and 12B illustrate alternative embodiments in which an element is positioned in a catheter to anchor the catheter.

As shown in FIG. 12B, a catheter 1204 is formed using a non-conductive filament 1218. Disposed in catheter 1204 are anchor plates 1254. As shown in FIG. 12A, anchor plates 1254 include a plurality of anchor points 1260 that, when positioned in catheter 1204, extend through the catheter stitches. Anchor points 1260 engage a patient's tissue to retain the catheter in a desired location.

In the embodiments of FIGS. 12A and 12B, anchor plates 1254 have an aperture 1258 therein that allows wires or other instruments to extend there through. In alternative embodiments the anchor plates do not include an aperture.

FIG. 13 illustrates an alternative embodiment of the present invention in which a conductive filament 1312 is knitted into an elongate tube 1330, referred to as conductive tube 1330. Conductive tube 1330 comprises longitudinally adjacent rows each stitched to an adjacent row. Conductive tube 1330 is disposed on a biocompatible non-conductive solid or hollow carrier member 1352. Conductive tube 1330 may function, for example, as a stimulating or ablation electrode. It should be appreciated that a plurality of conductive tubes 1330 may be disposed on carrier member 1352

FIG. 14A is a flowchart illustrating a method 1400 for manufacturing a knitted implantable catheter in accordance with embodiments of the present invention. As shown, method 1400 begins at block 1402 where at least one biocompatible, electrical non-conductive filament is provided. As noted above, numerous different types of non-conductive and conductive filaments may be provided. After the filaments have been provided, the method proceeds to block 1404 where the at least one non-conductive filament is knitted into an elongate tube of longitudinally adjacent rows.

FIG. 14B is a flowchart illustrating a variation of method 1400 of FIG. 14A, referred to as method 1410. As shown, method 1410 begins at block 1406 where at least one biocompatible, electrical non-conductive filament and at least one biocompatible, electrically conductive filament are provided. After the filaments have been provided, the method proceeds to block 1408 where the at least one non-conductive filament is knitted into an elongate tube of longitudinally adjacent rows. The at least one conductive filament intertwined with the at least one non-conductive filament.

As noted above, catheters in accordance with certain embodiments of the present invention include electrodes that are electrically connected to one or more components positioned external to a patient. However, catheters are subject to bending and stretching during implantation, as well as during normal operation, that may damage or break the electrical connection between the electrodes and the external components. As such, embodiments of the present invention provide strain relief to protect the electrical connection. As used herein, a strain relief refers to a non-linear section of a wire or filament between the electrode and external components. Upon bending or stretching of the catheter, the non-linear section of wire will expand to a longer length, thus preventing tension on the filament that results in a damaged electrical connection. Further details of strain relief in a knitted structure are provided in commonly owned and co-pending U.S. Utility Patent Application entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, the content of which is hereby incorporated by reference herein. All embodiments of strain relief described in “Knitted Electrode Assembly For An Active Implantable Medical Device” may be implemented in embodiments of the present invention.

It would also be appreciated that a catheter may be further processed following the knitting process. In one such embodiment, the catheter may be molded or sintered following the knitting process. For example, the knitted structure may be laser sintered, and fiber crossing points within the structure may be formed into bending anisotropies. In other embodiments, catheter may be processed (via molding, sintering, etc.) to create inflexible portions, such as a stiffened tip, or to create, for example, anchoring barbs that may be used to secure the catheter to the patient.

It would be appreciated that in alternative embodiments the catheter is dipped into, or molded over by, a second material to form a desired shape or configuration. For example, one or more portions of the catheter may sealed with an added material to prevent the entry of body fluid into the structure. It would be appreciated that a number of different post-processing methods may be implemented to form the final structure.

In still further embodiments, following the knitting process a catheter may be fully or partially covered by an outer structure, such as a tube. In such embodiments, the knitted structure would be stretched to reduce the width thereof, and the outer covering is placed over the desired portion. The knitted structure is then allowed to return to its previous non-stretched shape. The outer covering may be conductive, non-conductive or have both conductive and non-conductive sections, depending on the desired configuration. For example, an outer covering may be placed on the knitted structure such that conductive sections of the covering are disposed over the electrodes, while non-conductive sections extend over the other portions of the assembly. An outer structure may be beneficial to inhibit tissue growth into the knitted structure, to improve implantation by providing a smooth outer surface, to increase the surface area of conductive regions used to deliver electrical stimulation, increase stiffness of the catheter, etc.

As noted above, a catheter in accordance with embodiments of the present invention may include electrodes for delivery of electrical stimulation signals to a patient. In certain embodiments, a catheter is knitted from a non-conductive filament and has two or more conductive filaments extending there through. Disposed on the surface of the knitted catheter are two electrodes formed by creating a ball or other shaped structure on the distal end of the conductive filaments. For example, in certain embodiments the conductive filaments comprise platinum wire that is inserted into the knitted structure such that distal structure mates with the non-conductive filament, and is held in the appropriate position. The distal structure may be formed by, for example, melting the distal end of the conductive filament with a localized heat source, by bunching the conductive filament into the desired shape, attaching a bulk material piece (e.g. platinum foil) having the desired shape to the conductive filament by weld, crimping or other method, etc. Such embodiments are illustrated in commonly owned and co-pending U.S. Utility Application entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, the content of which are hereby incorporated by reference herein.

The present application is related to commonly owned and co-pending U.S. Utility Patent Applications entitled “Knitted Electrode Assembly For An Active Implantable Medical Device,” filed Aug. 28, 2009, “Knitted Electrode Assembly And Integrated Connector For An Active Implantable Medical Device,” filed Aug. 28, 2009, “Bonded Hermetic Feed Through For An Active Implantable Medical Device,” filed Aug. 28, 2009, “Stitched Components of An Active Implantable Medical Device,” filed Aug. 28, 2009, and “Electronics Package For An Active Implantable Medical Device,” filed Aug. 28, 2009. The contents of these applications are hereby incorporated by reference herein.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. All patents and publications discussed herein are incorporated in their entirety by reference thereto. 

1. A medical device, comprising: an elongate tubular knitted catheter comprising at least one biocompatible, electrically non-conductive filament arranged in longitudinally adjacent substantially parallel rows each stitched to an adjacent row.
 2. The medical device of claim 1, wherein the at least one non-conductive filament consists of a single non-conductive filament.
 3. The medical device of claim 1, further comprising: at least one biocompatible, electrically conductive filament intertwined with a row of the at least one non-conductive filament.
 4. The medical device of claim 3, wherein the at least one conductive filament comprises a plurality of conductive filaments each intertwined with one or more of the rows of the at least one non-conductive filament.
 5. The medical device of claim 3, wherein a section of the at least one conductive filament is wound around a section of the at least one non-conductive filament, and wherein the knitted catheter consists of: a plurality of rows of the least non-conductive filament having the conductive filament wound there around arranged in substantially parallel rows each stitched to an adjacent row.
 6. The medical device of claim 3, wherein the at least one conductive filament follows the same course as a section of the at least one non-conductive filament.
 7. The medical device of claim 6, wherein the at least one conductive filament is positioned on the exterior surface of the catheter.
 8. The medical device of claim 3, wherein the conductive filament is electrically connected to an electronics module, and wherein a section of the conductive filament between the intertwined portion of the filament and the electronics module provides strain relief.
 9. The medical device of claim 8, wherein a section of the conductive filament between the intertwined portion and the electronics module is woven into a plurality of the rows.
 10. The medical device of claim 1, further comprising: a steering element positioned in a distal end of the knitted catheter mechanically connected to one more externally positioned controls, wherein the controls are configured to actuate the steering element to alter the orientation of the distal end of the catheter.
 11. The medical device of claim 10, wherein the steering element comprises: a spring having coils of a diameter approximately equal to the inner diameter of the knitted catheter, and wherein one or more coils are coupled to the one or more control knobs.
 12. The medical device of claim 10, wherein the steering element comprises: a substantially planar element positioned in the knitted catheter having two or more points each configured to mate with rows of the catheter, and each mechanically coupled to at least one of the one or more control knobs.
 13. The medical device of claim 12, wherein the substantially planar element is star-shaped.
 14. The medical device of claim 10, wherein the steering element has an aperture extending there through.
 15. The medical device of claim 1, further comprising: one or more temperature activated shape memory components positioned in the knitted catheter; and one or more heating elements positioned adjacent to the shape memory components, the one or more heating elements configured to alter the shape of the shape memory components.
 16. The medical device of claim 1, further comprising: an agent delivery tube extending through the knitted catheter.
 17. The medical device of claim 16, wherein the distal end of the agent delivery tube comprises one or more agent delivery ports.
 18. The medical device of claim 1, further comprising: a biopsy device positioned in the catheter, the biopsy device extendable from the distal end of the catheter.
 19. The medical device of claim 13, further comprising: a removable stylet extending at least partially through the knitted catheter.
 20. The medical device of claim 1, wherein the knitted catheter is at least partially filled with a gel to prevent growth of fiburous tissue into the knitted catheter.
 21. The medical device of claim 1, further comprising: at least one active component positioned in the knitted catheter.
 22. The medical device of claim 1, wherein the at least one non-conductive filament comprises a drug-eluting polymer.
 23. The medical device of claim 1, wherein the at least one non-conductive filament comprises a thermo-softening plastic material.
 24. The medical device of claim 1, further comprising: a second elongate tubular knitted catheter formed from at least one biocompatible, electrically non-conductive filament arranged in longitudinally adjacent substantially parallel rows, each row stitched to an adjacent row, wherein the second tubular knitted catheter is positioned in the tubular catheter.
 25. The medical device of claim 1, wherein the tubular catheter has an inner diameter that is sufficient to receive at least one instrument.
 26. A method for manufacturing a knitted tubular catheter comprising: providing at least one biocompatible, electrically non-conductive filament; and knitting the at least one non-conductive filament into an elongate tube of longitudinally adjacent substantially parallel rows, each row stitched to an adjacent row
 27. The method of claim 26, wherein the at least one non-conductive filament consists of a single non-conductive filament, and wherein the method comprises: knitting the single non-conductive filament into a plurality of parallel rows each stitched to an adjacent row.
 28. The method claim 26, wherein knitting the at least one non-conductive filament further includes: intertwining at least one conductive filament with one or more of the rows.
 29. The method of claim 28, further comprising: winding the at least one conductive filament around a section of the at least one non-conductive filament prior to knitting; and knitting the least non-conductive filament having the conductive filament wound there around into substantially parallel rows each stitched to an adjacent row.
 30. The method of claim 28, further comprising: concurrently knitting the at least one conductive filament with a section of the at least one non-conductive filament such that the at least one conductive filament follows the same course as the section of at least one non-conductive filament.
 31. The method of claim 28, wherein the conductive filament is configured to be electrically connected to an electronics module, and wherein the method further comprises: forming a section of the at least one conductive filament between the intertwined portion and the electronics module into a helical shape.
 32. The method of claim 31, wherein the catheter is circular knitted, and wherein forming the section of the conductive filament into a helical shape comprises: forming the helical shape during the circular knitting process.
 33. The method of claim 31, further comprising: weaving the section of the at least one conductive filament between the intertwined portion and the electronics module into a plurality of the rows.
 34. The method of claim 26, further comprising: positioning a steering element in a distal region of the knitted catheter mechanically connected to one more externally positioned controls, wherein the controls are configured to actuate the steering element to alter the orientation of the distal end of the catheter.
 35. The method of claim 34, wherein the steering element comprises: a spring having coils of a diameter approximately equal to the inner diameter of the knitted catheter, wherein one or more of the coils are coupled to the one or more control knobs.
 36. The method of claim 34, wherein the steering element comprises: a substantially planar element positioned in the knitted catheter having two or more points each configured to mate with stitches of the catheter, and each mechanically coupled to the one or more control knobs.
 37. The method of claim 26, further comprising: positioning one or more temperature activated shape memory components in the knitted catheter; and positioning one or more heating elements adjacent to the shape memory components, the one or more heating elements configured to alter the shape of the shape memory components.
 38. The method of claim 26, further comprising: positioning an agent delivery tube in the knitted catheter.
 39. The method of claim 26, further comprising: positioning a biopsy device in the knitted catheter, wherein the biopsy device is extendable from the distal end of the catheter.
 40. The method of claim 26, further comprising: positioning a removable stylet at least partially in the knitted catheter.
 41. The method of claim 26, further comprising: filling at least the stitches of the knitted structure with a gel to prevent growth of fiburous tissue into the knitted catheter.
 42. The method of claim 26, further comprising: positioning at least one active component in the knitted catheter.
 43. The method of claim 26, wherein providing the one or more non-conductive filaments comprises: providing at least one non-conductive filament comprising a drug-eluting polymer.
 44. The method of claim 26, wherein providing the one or more electrically non-conductive filaments comprises: providing at least one non-conductive filament comprising a thermosoftening plastic material.
 45. The method of claim 26, wherein the tube has an inner diameter that is sufficient to receive at least one instrument.
 46. An implantable medical device, comprising: a non-conductive tubular carrier member; and a knitted conductive tube mounted on the carrier member comprising at least one biocompatible, electrically conductive filament arranged in longitudinally adjacent parallel rows, each row stitched to an adjacent row.
 47. The medical device of claim 46, further comprising: a plurality of knitted conductive tubes each formed from separate conductive filaments and each mounted on the carrier member.
 48. The medical device of claim 46, wherein the at least one conductive filament consists of a single conductive filament.
 49. The medical device of claim 46, wherein the at least one conductive filament is electrically connected to an electronics module, and wherein a section of the conductive filament between the knitted tubular member and the electronics module has a helical shape. 